This invention relates to a power transfer arrangement for providing power to the electrical system of a building, such as power supplied from a standby generator.
Portable generators may be used in certain situations to feed electrical power to residential and commercial load circuits during a utility power outage. These systems in their most basic form include a generator or other auxiliary source of power positioned exteriorly of a building. The generator is connected to a transfer switching mechanism which continues the electrical path through circuit breakers associated with the transfer switching mechanism to supply power to certain selected circuits of the load center as determined by the transfer switching mechanism circuit breakers. The circuits of the transfer switching mechanism are wired to selected circuits of the load center through wiring housed within a conduit extending between the load center and the transfer switching mechanism.
The present invention relates to a power transfer switching mechanism for interposition between a remote power inlet box and the electrical load center of a building. Such a switching mechanism typically includes a cabinet having a panel provided with an opening for accommodating power input structure, such as a socket-type power input receptacle. The input receptacle is adapted to selectively receive a plug connector electrically interconnected with a source of auxiliary power such as a generator, and is interconnected with a bus bar within the cabinet. Circuit breakers are mounted to the bus bar for receiving power from the generator through the input receptacle to provide auxiliary power to selected circuits of the load center. Transfer switching mechanisms of this type are commercially available from Reliance Controls Corporation of Racine, Wis. under the designation GEN/TRAN.
While the above-described transfer switching mechanism provides an extremely convenient and simple arrangement for establishing a selective connection with the power inlet box, it is sometimes desirable to provide a power transfer switching mechanism without a pronged power input receptacle in its cabinet panel, in which the remote power inlet box is wired directly to the transfer switching mechanism. One such arrangement is shown and described in copending application Ser. No. 09/021,670, filed Feb. 10, 1998, the disclosure of which is hereby incorporated by reference, which contemplates a set of terminals mounted to the underside of the main panel of the transfer switch mechanism. This transfer switching mechanism includes a specially made cabinet which omits the opening for the power input receptacle. While this construction is highly satisfactory for directly wiring the power inlet box to the transfer switching mechanism, it requires modifications to conventional cord-connected transfer switch cabinets in omission of the input receptacle opening and mounting of the terminals within the cabinet.
It is an object of the present invention to provide a transfer switching mechanism having a cabinet equipped with a cover plate terminal assembly for preventing access to the interior of the cabinet and providing interconnection of a terminal arrangement within the cabinet. It is a further object of the present invention to provide a power transfer arrangement having a cover plate for covering a socket opening formed in a panel of the cabinet in combination with a terminal connector for receiving input power and providing electrical connection to the components of the transfer switching mechanism. It is also an object of the present invention to provide a power transfer device which ensures that a reliable connection is established with a generator when power is supplied to the transfer device. Another object of the present invention is to provide a transfer switching mechanism which is easy to install and which operates generally similarly to known transfer switching mechanisms. Still another object of the present invention is to provide a method of constructing a power transfer device which may be provided with either a socket-type power input receptacle or a terminal-type power input arrangement.
The invention contemplates an improvement in a power transfer arrangement for supplying power from a generator to the electrical system of the building. The power transfer arrangement has a power transfer device adapted for interconnection with the building electrical system and includes a cabinet having wall structure provided with an opening for accommodating a socket-type power input receptacle. The wall structure also supports various other electrical components of the power transfer device thereon. The invention resides in a terminal arrangement in the power transfer device and a cover engageable with the wall structure for covering the opening and preventing access to the terminal arrangement. The terminal arrangement is mounted to the cover, and enables power to be transferred from the generator to the remaining components of the power transfer device. The components of the power transfer device include a set of switches mounted to the wall structure for controlling the supply of power from the power transfer device to the building electrical system. The terminal arrangement includes a set of power input terminals for establishing an electrical connection between the power transfer device and a power inlet arrangement interconnected with the generator. The power input terminals are located within a terminal compartment defined by the cabinet at a location spaced from the set of switches. The electrical components on the wall structure also include a power output receptacle for selectively delivering generator power to a load plugged into the receptacle. The electrical components on the wall structure further include a pair of watt meters for displaying the amount of power provided by the generator, and a set of circuit breakers, with each circuit breaker being associated with one of the switches. A set of power input wires are adapted to be connected to the power input terminals for supplying power to the power transfer device from the generator through the power inlet arrangement. A conductor extends between the terminal arrangement and each of the watt meters, and a pair of conductors extend between the terminal arrangement and the power output receptacle.
The invention further contemplates an improvement in a power transfer device adapted for interconnection with the electrical system of a building and including a cabinet having a face plate provided with an opening for accommodating a power input receptacle adapted to receive a plug connector electrically connected to a generator. The face plate also supports various other electrical components of the power transfer device thereon. The invention is in the form of a terminal compartment defined by the cabinet, a set of terminals associated with the electrical components located within the cabinet, and a cover plate terminal assembly removably connected to the face plate and covering the opening to prevent access to the terminal compartment. The cover plate terminal assembly is also electrically connected to the electrical component terminals in the cabinet interior. The cover plate terminal assembly includes a cover plate, a terminal connector and spacing structure interposed between the cover plate and the terminal connector for spacing the terminal connector from the cover plate. In the preferred embodiment, the spacing structure is comprised of a Z-shaped bracket having a first end portion fixed to the face plate, a rearwardly extending portion joined to the first end portion and a second end portion fixed to the terminal connector by fasteners which are passed through the terminal connector and are threaded into the second end portion. In another embodiment of the invention, the spacing structure is comprised of at least one shimming-type element. The pair of fasteners extends through the terminal connector and the shimming-type element, and each fastener is screw threaded into the cover plate. The face plate is formed with a set of apertures located around the opening. The cover plate is formed with a set of through holes which are aligned with the face plate apertures, and a set of fasteners extends through the apertures and each fastener is screw threaded into the through holes to fix the cover plate terminal assembly relative to the face plate.
The invention also relates to a method for constructing a power transfer device having electrical components for supplying power from a generator in electrical communication with a separate power inlet to the electrical system of a building. The method includes the steps of providing a cabinet with an interior within which a set of connections corresponding to the electrical components is located; forming the cabinet with wall structure having an opening formed therein, and mounting a cover having a terminal connector over the opening and against the wall structure for preventing access to the terminal compartment and providing power from the generator to the electrical components of the power transfer device.
Another aspect of the invention relates to a power transfer device provided with electrical components for supplying power from the generator in electrical communication with a separate power inlet arrangement to the electrical system of a building. The power transfer device includes a cabinet defining an interior within which a set of terminals corresponding to the electrical components is located. The cabinet has a wall structure provided with an opening formed therein, and the wall structure supports the electrical components. A cover is mounted against the wall structure over the opening and has a terminal connector connected to the cover for preventing access to the cabinet interior and providing power to the set of electrical component terminals.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.